Pusher



Aug. 16, 1949. 5] T N 2,479,074

PUSHEB Filed Nov. 20, 1944 INVENTOR. STODDARD B MART/N Patented Aug. 16,1949 UNITED.- STATES PATENT- *oFFlcE garet J, Martin ApplicationNoveniber 20, 1944, Serial N ssau;

9C lain 1s. (01. 294-62).

This invention relates to pushers for automatic screw machines and thelike. I I I Each spindle of an automatic screw machine ordinarilyincludes'a rotating collet tube having a collet at its forward end whichis arranged-to be compressed radially to grip and rotate a bar of stockfed axially through the collet tube." At the end of each cycle ofoperations'of the machine, the projecting end of stock is cut off fromthe bar. the collet opens, a new lengthof stock is fed forwardly, andthe collet is againclosed to grip the stock and repeat the cycle ofoperations. The stock is ordinarily'fed forward by a pusher NationalBank of Cleveland, executorot said Stoddard B. Martin, deceased,assignor to,Mar-

enable the tight grippingaction'tolbe prevented carried by areciprocating pusher tube arranged between and coaxial with the collettube and the stock. 1 l i To simplifythe operations involved in changingthe machine from one size stock to another it.

has been proposed to use interchangeable stock gripping pads removablymountediin a shell or, the like carried onthe end of thereciprocatingpusher tube. 7 Many difficulties have'lbeen encountered, however, inassembling 'the pads or lbushings in the pusher shell so that they areproperly held in place during operation of'the machine-and at the sametime are quickly and easily removable. V

The principal object of, this invention is to overcome thesedifliculties andtomount removable and replaceable pads or bushings in apusher shell in such a manner that'they may be readily removed andreplaced without the use of special tools and at the same time aresecurely heldin place during operation of the machine.

Other objects of the present invention are to improve the constructionof the removable bushing fora pusher of thisity'pej "to obtaingboth aresilient gripping action and 'a' hardened non resilient stock engagingsurface in a one piece bushing; and to improve the bushing constructionso as to facilitate its heat treatment to obtain a resilient portion anda hardened nonresilient stock grippingportion.

It is also desirable in pushers of provide a one way stock grippingaction so that sufficient grip can lbe obtained on the stock to" insureaccurate feeding and prevent rebounding when the stock strikes'the stockgauge while minimizing the grip on thestock during the retracting strokeof; the pusher soas'to minimize wear and avoid scratching or marring thestock. Accordingly, further objects of this invention are to obtain arelatively light gripping action on the retracting stroke withanincreased or substan tially positive grip on, the feeding stroke; and tothis type to when desired to permit removal 'of th'e stock from themachine. Other objectsandadvantages 0 this invention will appearhereinafter. I g

In the accompanying drawings:

Fig. 1 is a side elevation of a pusher constructed in accordancewith'the present invention} Fig. 2 is-a cross section on the line 2-2 ofV Fig. 3 is a side elevation-of the pusher shown in Fig. l with theparts arranged to prevent a tight gripping actionon the forwardstroke;

Fig. 4 is 'a side-elevation on a reduced scale showing the bushing beingremoved from the pusher shell; 7

Fig. 5 is a side elevation of a modified form em- .bodying the improvedassembly feature of this invention without a wedging or tight grippingacward end the shell lflisfprovided with oppositely disposed extensions.1, I terminating in relatively short inwardly directed flanges ll. Theextene sions'll arecontinuations of'the body of the shell and arerelatively short circumferentially as illustrated in Fig. 2.'Preferably-the circumferential extent of each extension is about 30although this dimension can be increased the 7 smaller size pushers anddecreasedin the larger sizes if desired.

The shell l'flis iormed internally. with a bore l3 extended inwardlyfromrthe'rear :end of the shell and leaving a wallthicknesscorresponding to the thickness of the pusher tube to which theshell is secured. The e'xtensi'ons are "formed with a counterbore M ofgreater diameter than the more 13 so that the thickness of theeXtensions' H is less than the thickness of'the remainder of theshellwall. Thebores Band 14 are connected by a conical shoulder 15 forming awe'd'ging surface on the shelh; 5 The preferred for-moi bushingillustrated "in Figs. 1 to 4 consists'of a sleeve l'6 splitlongitudinally from end to end at one 'point as indicated at H.Thesleevejii has aii internalfbore l 860; a size to fit aparticular size o f stock andat its rward a d wa me w i 'x nt ho l n n iip ardb'. gsho tn st nce a d ormin an integral ring 2'0 at the forward" end of'thewith a groove 22 extending from the ring 26 rear-* wardly to a shoulder23. Beyond the shoulder 23 the sleeve is formed with a substantiallycylindrical portion 24 of a diameter tojfitsnuglywithin the bore l4 andat its rear end thesleeve is formed with a conical portion 25' arrangedto fit within and cooperate with the conical portion I5 within theshell. e y

The depth of the groove '22 with respect to the cylindrical portion 24is equal to the depth of the flanges I2 on the extensions H so that theinner surfaces of these' fia nges l2 bear in the groove 22 while thecylindrical portion 24 bears in the bore HL. Theaxial length of thegroove 22 is determinedby the. desired overlapping length of theconical, surface IS in the shell It and the conical surface 25011 thebushing so that when the bushing is. pulled forward until the shoulder'23 engages the rear sides of the flanges l2 the rear end of the taperedportion 25 just clears the forward edge of the shell It between theextensions l! asshown in Fig. 3.

The shell I is conveniently made from a solid tube by boring out theconical shoulder l and the bore I 4, leaving metal of the initialthickness of the tube wall to form the-flanges [2. The portions of theshell between the extensions II can then be milled away Q both sidestothe desired length and width. The extensions ll are then given aninward set and the entire shell is spring tempered. l

The bushing is made from metal capable of being given a spring temperand of being hardened, such as medium to high carbon steel. The bushingcan be'conveniently made from a length of tubing with an internal 'borel8 equal to the diameter of the stock the bushing is to grip. Afterforming the counterborels, the split 11 and the slots 2! and'jturning'the exterior sur-' face, the entire bushing is given an inward set topartially close the split I! and the rear portion of the bushing isgiven an inward set to partially close the slots 2|. The bushing is thenheat treated to harden the inner surfaceforming the bore #8 to thedegree desired so as to form hardened wear resisting surfaces. The ring20 is then annealed or drawn back to a spring temper, which can-bereadily accomplished-in the usual manner without .interfering with-thehardness of the stockengaging portions of the bushing.

The bushing andshell may be readily assembled by simply placing the endsof the flanges 12 against one side of the groove 22 immediately adjacentthe shoulder 23 and pressing the bushing laterally into axialalignmentwith the, shell It. This action is permittedbecause the comin lth of the cylindr cal portion 24. and the conical portion 25 01; thebushing do not substantially exceed the length of the extensions Hbehind the flanges 12. To facilitate the spreading of the extensions l}the bushing may be tipped as shown in Fg. sand then pivoted into axialalignment with the shell. V

Means may also be provided to prevent grip- Ping engagement 9f the qenie sl t ssesl nd 4 25 when desired. As illustrated in Figs. 1 to 3 asplit band 28 may be snapped over the bushing I 6 in the groove 22 andpositioned at the forward end of the groove 22 against the integral ring20. The band 28 is provided with a pair of relatively long extensions 29adapted to sub stantially abut the shoulder 23 so as to hold the band inplaceand with a pair of shorter extensions terminating in shoulders 30adapted to be brought into engagement with the outer ends of the flangesl2 as shown in Fig. 3 to prevent the bushing I6 from moving axially intothe shell [0 and thus prevent gripping engagement between the conicalsurfaces I5 and 25.

'In normal operation the stock S is intermittently rotated in onedirection when it is gripped by the collet carried by the collet tubesurrounding the pusher tube and shell Ill. The bushing 16 by reason ofits resilient grip on the stock tends to rotate with the same and totransmit this rotation to the shell ID. The extensions 29 are formedwith lateral shoulders 3| arranged to engage the adjacent ends of theflanges 12 when the stock is rotated in the normal direction of rotationof the machine. The lateral shoulders 3| extend in an axial direction soas not to interfere with therelative reciprocation of the bushing I6 andthe shell Hi. When it is desired to prevent gripping, engagement betweenthe conical surfaces 15 and '25 the stock may be pushed forward androtated in the direction opposite to its normaldirecticn of rotation soas to bring the shoulders 30 over the outer ends of the extensions H, inthe position shown in Fig. 3, so that the stock can be pulled rearwardlyout of the pusher without bringing the conical surfaces l5 and 25 intowedging engagement. 7

It is to be understood that the shoulders 38 and M may be integral withthe bushing 36 or may be formed in any other desired way, but themounting of these shoulders on the spring ring 28 is preferred sincethis permits all of the machining on the outer surfaces of the bushingto be done by turning and the rin 28 may be stamped out from sheet metaleasily and inexpensively. It will also be understood thatthe ring 28 andthe shoulders 30, and 3| may be omitted when desired.

In operation the pusher tube to which the shell I0 is attached isadvanced or moved to the left, as seen in Fig. 1, when a new length ofstock is to be fed forwardly. The inward set given to the bushing andthe. spring temper of the ring 20 provides a resilient grip of thebushing on the stock'so that the bushing remains in place while theshell mOVes to'the left, bringing the conical surfaces l5 and 25 intoengagement. These surfaceswedge the bushing sections inwardly againstthe stock, providing a tight grip during the feeding motion andpreventing rebounding when the stock strikes the gauge. On theretracting stroke the shell Hi moves to the 7 right as seen in Fig. 1.During this motion the shell slides over the bushing until the flangesl2 engage the shoulder '23 and pull the bushing to the right over thestool: against the friction provided by the spring grip of the bushing.When no stock is disposed within the bushing the latter collapses to theextent of its initial inward set. The flanges t2, however, remain insnug engagement with the bottom of the groove 22 by reason of the inwardset and spring tempergiven to the. extensions ll. Thus. the bushingcannot escape from the shell, when thereisj no. stock withinthe bushing.V

In the form shown in Fig. the bushing is assembled in the pusher in thesame manner previously described but operates only with a spring gripand without the wedgingaction on the forward stroke. The shell II!) issubstan-- tially the same as the shell IIl illustrated in Figs; 1 to 4,and is provided with the extensions I I I and flanges i l2. The bushingI I6, however, is formed with a groove I22 which needs to be onlyslightly greater in axial extent that the axial length of th flanges II2. Behind the groove I22 the bushing is provided with a substantiallycylindrical portion I24 of a diameter to fit the bore I I4 in theextensions II I. The axial length of the cylindrical portion I 24 may besubstantially equal to the combined axial lengths of the cylindricalportion 24 and the conical portion 25 shown in Figs. 1 and 3. Theconstruction, method. of assembly and operation of the bushing I I6 areotherwise the same as described in connection with Figs. 1 to ,4inclusive.

A further modified form of bushing is illustrated in Fig. 6. In thisfigure the shell I0, extensions II and flanges I2 may be the same as'illustrated in Figs. 1 and 3. The bushing 2H5 is formed externally witha cylindrical portion 225 and a conical portion 225 arranged to fit theconical portion I5 in the shell I0. In advance of the cylindricalportion 224 the bushing is formed with a shoulder 223 and a conicalgroove 222, preferably having a smaller degree of taper than the conicalsurfaces 225 and I5. The conical surface 222 terminates at the rear endof the integral ring 220. In this embodiment on the forward stroke ofthe pusher shell the conical surface I5 in the shell engages the conicalsurface 225 on the bushing and increases its grip. At the same time theinner surfaces of the flanges I2 ride up on the conical surface 222providing a further increase of the grip of the bushing by reason of theinward set and spring tension of the extensions II. However, before theconical surfaces I5 and 225 have been wedged together with sufficientforce to lock the bushing on the stock the forward; edges of the flangesI2 engage the shoulder at the rear end of the ring 220 and preventfurther tighteningof the wedging surfaces. With this arrangement it isunnecessary to provide means to hold the wedging surfaces out ofengagement when it is desired to withdraw a bar from the pusher sincethe increased gripping force pro-. vided by the wedging surfaces islimited by the engagement of the flanges I2 with the rim 220. Thus atighter grip is provided on the feeding stroke than on the retractingstroke but the grip never tightens sufficiently to lock the pusher tothe stock.

Although preferred embodiments of the invention have been described inconsiderable detail it will be understood that many variations andmodifications thereof can be resorted to within the scope of theinvention. For example, the limitation of the gripping force in theembodiment shown in Fig. 6 may also be used in the arrangement shown inFigs. 1 to 4 inclusive with a single set of wedging surfaces in place ofthe abutments provided by the spring ring. Similarly the quick assemblyfeature may be used with other forms of bushings and the improvements inthe bushing itself may be used with otherkinds of pusher shells.

I claim: 7

1. A pusher comprising a shell having extensions projecting axially fromits forward edge.

said extensions being formed with" rearwardlyfacing abutment shoulderson their inner surfaces,

a bushing adapted to grip stock to be. fed fitting between saidextensions, said bushing being formed withforwardly facing abutmentsurfaces adapted to-engage' said rearwardly facing abutment shoulders,the length of said bushing from said forwardlyfacing surfaces to therearward end of said bushing being substantially no greater than thelength'of said extensions from said rearwardly facing abutment shouldersto the forward edge of said shell, and'the circumferential spacingbetween at least two adjacent edges of said extensions being such thatsaid bushing may be assembled insaid shell by into position between saidextensions.

2 A pusher comprising a sions projecting axially from its forward edge,said extensicns being formed with rearwardlyfacing abutment shoulders ontheir-inner surfaces, a bushing adapted to grip stock to be fed fittingbetween said extensions, said bushing being formed with forwardly facingabutment surfaces adapted to engage said rearwardly facing abut- 'mentshoulders, said projections being tensioned inwardly so as to engageresiliently with said bushing forwardly of said forwardly facingabutment surfaces, the length of said bushing from said forwardly facingsurfacesto the rearward end of said bushing being substantially nogreater than the length of said extensions from said rear wardly facingabutment shoulders to the forward edge of said shell and thecircumferential spacing between at least two adjacent edges of saidextensions being such that 7 said bushing may be assembled in said shellby being snapped laterally into position between said extensions.

3. A pusher comprising a shell, a bushing within said shell arranged togrip stock to be fed, cooperating wedging surfaces on said bushing andsaid shell arranged to increase the grip of said bushing on said stockwhen said shell moves forwardly with respect to said bushing,cooperating abutments on said shell and bushing adapted to engage andprevent relative movement of said shell and bushing in the oppositedirection, said shell being formed with an extension projecting axiallyfrom the forward edge thereof and a forwardly facing abutment on theforward end of said'extension,

operating wedging surfaces on said bushingand said shell arranged toincrease the gripof said bushing on said stock when said shell movesfor+ wardly with respect to abutments on said shell and bushing adaptedto engage and prevent relative movement of said shell and bushing in theopposite direction, said shell being formed with an extension projectingaxially from the forward edge thereof and a forwardly facing abutment onthe forward end of said extension, and a spring band surrounding andgripping said bushing and having a rearwardly extending abutmentmember,said member being adapted,in one angular relation of said band and saidshell, to pass said extension, and, in another angular relation of saidband and said shell, to

being snapped laterally shell having extenand a ring surrounding saidbLlSh:-' 'ing and having a rearwardly extending abutment member, saidmember being adapted, in one angular relation of-said ring and saidshell, to pass said 1 said bushing, cooperating.

engage said forwardly facing abutment and pie-f vent engagement of saidwedging surfaces.

5. A pusher comprising a shell, a bushing within said shell arranged togrip stock to be fed, the rear end of said bushing bein formed with aWedging surface, a cooperating wedgin'g surface on the interior of saidshell, said surfaces being arranged to increase the rip of said bushingon said stock when said shell moves forwardly with respect to saidbushing, cooperating abutments on said shell and bushing adapted toengage and prevent relative movement of said shell and bushing intheopposite direction, said shell being formed with an extension projectingaxially from the forward edge thereof and a forwardly facing abutment onthe forward end of said extension, and a ring surrounding said bushingand having a rearwardly extending abutment member, said member beingadapted, in one angular relation of said ring and said shell, to passsaid extension, and, in another angular relation of said ring and saidshell, to engage said forwardly facing abutment and prevent engagementof said Wed'ging surfaces.

6. A pusher comprising a shell having a pair of circumferentially spacedresilient axial extensions at its forward end, said extensions carryingrear- Wardly facing abutment shoulders on their inner surfaces, abushing adapted to grip stock to be' fed, said bushing having an annularforwardly facing abutment surface adapted to contact said rearwardlyfacing abutment shoulders to pull said bushing rearwardly when saidshell moves rearwardly with respect to the stock, the circumferentialspacing between said extensions on at least one side beingsuch that saidbushing may be assembled in said shell, by being snapped laterally intoposition between said extensions, and said annular forwardly facingabutment surface being of sufiicient circumferential extent to engagesaid rearwardly facing abutment shoulders in all angular positions ofsaid bushin with respect tosaid shell.

7. A pusher comprising a shell having a pair of circumferentially spacedresilient axial extensions at its forward end, said extensions carryingrearwardly facing abutment shoulders on their inner surfaces, a bushingformed to resiliently grip stock to be fed, said bushing having an'annular forwardly facing abutment surface adapted to contact saidrearwardly' facing abutment shoulders to pull said bushing rearwardlywhen said shell moves rearwardly with respect to 2 the stock, saidextensions being bent inwardly and constructed to engage resilientlywith said bushing in advance of said annular abutment surface, thecircumferential spacing between saide xtensions on at least one sidebeing such that said bushing may be assembled in said shell, by beingsnapped laterally into position between said ex tensions, and saidannular forwardin facing abutment surface being of suflicien'tcircumferential extent to engage said rearwardly'facing' abutmentshoulders in all angui'ar positions of said bushing with respect to saidshell.

' 8. A pusher comprising a shell having extensions projecting axiallyfrom'its' forward edge, said extensions beingh forinecl with rearwardlyfacing abutment shoulders on their inner surfaces, a bushing adapted tofit between said extensions and to grip stock to be fed, said bushingbeing formed with forwardly facing abutment surfaces adapted to engagesaid rearwardly facing abutment shoulders, said projections being tensio'ned inwardly so as to engage resiliently with said bushing forwardlyof said forwardly facing abutment surfaces, the forward edge of saidshell and the rearward end of said bushing being formed with cooperatingabutment surfaces, the length of said bushing from said forwardly facing' surfaces to the rearward'end of said bushing beingles's than thelength of said extensions from said rearwardly facing abutment shoulderst6 the forward edge of said shell, and the circumferential spacingbetween at least two adjacent edges of said extensions being such thatsaid bushing may be assembled in said shell by being snappedlaterallyinto' position between said' extensions.

9. A pusher comprising ashell having a pair of circumferentially spacedextensions projecting axially from forward edge, said extensions beingformed with rearwardly facing abutment shoulders on their innersurfaces, a bushing adapted to fit between said extensions and to gripstock to be fed, said bus-hing being formed with forwardly facingabutment surfaces adapted to engage said rearwardly facing abutmentshoulders, the forward edge of said shell and the rearward end of saidbushing being formed with cooperating abutment surfaces, the length ofsaid bushing from said forwardly facing surfaces to the rearward end ofsaid bushing being less than the length of said extensions from saidrearwa rdly facing abutment shoulders to the forward edge of said shell,and the circumferential spacing between at least two adjacent edges ofsaid extensions being such that said bushing may be assembled in saidshell by being sna g'iped' laterally into position between saidextensions.

STODDARD B. MARTIN.

REFERENCES CITED The following references are of record in the file ofthis patent: V

UNITED STATES PATENTS 1 Number Name Date 1,490,559 Fancher et a1. Apr.15, 1924 2,187,090 Martin Jan. 16, 1940 2,299,972 Gallen et al Oct.2'],- 1942 2,343,364 Bochen'ekl Mar. 7,. 1944 2,362,494 Martin 1 Nov.14', 1944 2,363,889 Martin Nov. 28, 1944 2,363,890 7 Martin Nov. 28,1944

